"Synonyms: A-1 Apolipoprotein; Alpha Apolipoprotein; Apo A-1

Why It Is Done

Screen for hyperlipidemia and/or a family history of CAD or peripheral vascular disease Assess your risk of developing heart disease Monitor the effectiveness of lipid treatment and/or lifestyle changes

Test Overview

Apolipoproteins are the protein component of lipoproteins - complexes that transport lipids throughout the bloodstream.

High-density lipoprotein (HDL - the ""good"" cholesterol), goes out to the tissues and picks up excess cholesterol, then transports it back to the liver where it is either recycled for future use or excreted into bile. HDL's reverse transport is the only way that cells can get rid of excess cholesterol. It helps protect the arteries and if there is enough HDL present, it can even reverse the build up of fatty plaques in the arteries

Apolipoprotein A activates the enzymes that load cholesterol from the tissues into HDL and allows HDL to be recognized and bound by receptors in the liver at the end of the transport.

There are two forms of apolipoprotein A, Apo A-I and Apo A-II. The concentration of Apo A-I can be measured directly and tends to rise and fall with HDL levels. This has led some experts to think that Apo A-I may be a better indicator of atherogenic risk than the HDL test.

How To Prepare

Patient must be fasting 12 to 14 hours. "